Time-frequency harmonic wave analysis method of composite micro-Doppler signals
In the time-frequency analysis of the echoes from targets with composite micro-motions,there is a problem that the energy of time-frequency strip is difficult to focus,which affects the extraction and analysis of the target's micro-Doppler feature.To solve this problem,this paper proposes the concept of time-frequency harmonic stripes and corresponding time-frequency transformation methods.Based on the assumption that the composite micro-motions include central motion components and high-frequency motion components,firstly,spline function is used to fit the frequency curve of the central motion component,and therefore construct the time-frequency transform kernel is constructed.Then,parameterized time-frequency transform is used to convert the composite micro-Doppler signal in the time domain to harmonic stripes on the time-frequency plane.Compared with traditional methods such as short-time Fourier transform and pseudo Wigner-Ville distribution,the proposed method can significantly improve the energy aggregation and spur suppression of time-frequency transform of radar echoes from composite micro-motion targets.Simulation results verify the effectiveness of the proposed method and its adaptability to low signal-to-noise ratio(SNR)conditions.
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